Keeping customised values

By default, all the tasks will override the value of a variable (reading the content from a file, pom, incrementing it, or from another variable).

There's an option to change this behaviour: if the destination variable was customised by the build (Run->Run Customised), it would actually keep its value.

This is very convenient when doing a release: so the default would be reading the pom file (for example), but running the build with the customised build would keep the value especified.